Radio receiving system



Jul y 24, 1934. G RQYDEN 1,967,328 RADIO RECEIVING SYSTEM Original Filed Jan. 4, 1928 IN V EN TOR.

Patented July 24, 1934 UNITED STATES P'ATENTOF 1,967,328 F'IICE Federal Telegraph Company, San Francisco,

Calif., acorporation of California Application January 4,

1928, Serial to. 244,478

Renewed December 10, 1929 8 Claims.

My invention relates broadly to a broadcast radio receiving apparatus and'more particularly toaa radio receiver having a multiple numberoi stages oi electron tube amplification with the. electron tube circuits supplied with power frompan alternating source.

An object of: this invention is to provide an improvementin. an alternating current radio receiverwhereby the number of component parts in the filter system may be reduced, and the size of-the. individual; parts maybe reduced, without sacrificing. quality of reproduction or introducing anyinterferinghum. v

Another object of my invention is to provide radioreceiving apparatusincluding a radio frequency amplifier, detectorand audio frequency amplification. system inf-which rectified current from. an. alternating current power source is supplied first-to the lastqpower stage of an audio frequency amplifier and then tothe radio and audio frequency amplification systems for the more; economical;v consumption. or energy from the powerfisourcer a v s i Still" another: object of: my inventon is to provide an alternating, current: powerl operated radio JreCCiViBg apparatus :wherein the: filter sys- :tem: is provided with; a," choke coil arranged for the double purpose; ofpreventing; the audio= frequency component of the platezcurrent of the final power stage of amplification from passingaback through the: filter circuitby.forcing: this current through; the loud; speaker; systerm, at the -same=time that the choke coiljoperates to suppress. ripple from the rectification: system in theapower supply: circuit. 7

Other'aand: further objects of my invention reside; in; the circuit" arrangement for an alternating currentr operated radio receiver as set forthimore clearly-inwthe specification and-drawi'ng.v In thejdrawing an antenna-1 is connected toground 2 through; the: primary 4- of a transiormerrrlis: The: secondary winding system of the coupling system 3 may be of;the variometer type tuned ibyragzvariable;condenser: 6. The receiving aDPflra-tuswincludesystages of tuned. radio frequency-amplification representedat. 7, 8 and 9 witl r a-i detector 10 connected to i the final; stage of *radijoprfrequency amplification, The stages of {thevaudlo;frequency amplification; system include the electron, tubeamplificationistagell coupled to audio:frequency-transformer l3 and thezpower ,stagez-otgaud-io ;frequency amplification 12:: coupled-p; tovtheoutput: of; stage 11. through audio: frequency transformer 14. Alternating currentcis suppliedto the cathode circuit for-the three; Estagesy; of: radio frequency amplification 7, 8 and 9 and the stage of audiop'irequencyamplification-ell'gthrou hgconnections 45 which extend to winding 23 on the power transformer 18. Power transformer 18 includes primary winding 19 and secondary windings 20, 21, 22, 23 and 24. i The primary winding 19 is disposed in series with the power supplycircuit on tap 25 controllable by means of switch 26. A full' wave rectifier 28 is provided having its cathode heated from winding 20 and having its anodes connected to the opposite terminals of secondary winding 21, The rectifier connects to a filter oir cuit including choke coil 31and condensers and 33. A choke coil 32 is disposed in series with the filter circuit and connects at one end thereof with the plate electrode of the final stage of power amplification represented at 12 and to the loud speaker circuit including condenser 34 and actuating winding 35. Theoppositeend of the choke coil 32 connects to the filter system. Resistors 39, and 41 are arranged in series and sections thereof shunted by means of condensers 37and 38 as shown. The same rectified cur rent from the rectification system is first supplied to the final stage of power amplification 12 and then: to the radio frequency amplification stages '7, r 8 and 9, audio frequency amplifier stage 11, and'then to the; plate circuit of the detector 10. In order toobtainminimum hum at the speaker 36'the filament tcircuitis bridged by means of a potentiometer l5 having a tap connection 15a extending therefrom: to a point intermediate resistors 40 and 41-. The tap 15a connects between condensers 16 and 17, which are in tumconnected between the input circuits of the several tubes constituting the radio frequency amplifier, detector andfirst stage of audio frequency amplification and between the output circuits of three stages of radio frequency amplification'and the first stageof audio frequency amplification. The required grid biasing poten tials for the amplifier tubes are obtained from thepotentials acrossresistancesBQ and 41. The loud speaker 36 is actuated'by winding 35 which controls the movement of the armature, which in turn impressesvibrations upon the sound reproducing diaphragm 36. The winding 35 is connected in series with condenser 34, a connection also being taken from condenser 34 to one end of the choke coilt32. This arrangement enables the audiofrequency component of the reproduced broadcast energy to be forced through the loud speaker system and is prevented from backing through to the filter circuit by means of choke coil 32 at the same time that the choke coil 32 operates to suppress ripple from rectifier ,tube- 28; preventing such ripple from reaching loud-speaker winding 35. A pilot light 43 is connected through leads 44 across secondary winding 22, which serves to supply filament heatingcurrent to the finalstageof power amplification represented at 12. Secondary winding 24 serves to supply current to the heater 46 of the detector tube 10. In the circuit arrangement shown I employ a detector tube of the indirect emitter type in which a cathode 10a. is brought to an electron emitting temperature by means of the heater 46.

In the operation of the radio receiving apparatus described herein I have found that there is less power drawn from the lighting socket than heretofore possible in alternating current power operated radio receivers of a similar number of amplification stages. Consequently, the power transformer may be smaller and built more economically. The current passing through the choke coils is less than is normally required permitting more inductance for the same amount of copper and iron. The circuit arrangement uses two choke coils instead of three as heretofore normally required in power operated receivers. The condensers in the filter system may have less capacity because of greater inductance of the choke coils.

The power operaterd radio receiver described herein has been found to be extremely practical in construction, and While I have described preferred embodiments of the circuitarrangement of my invention, I desire that it be understood that modifications may be made and that no limitations upon my invention are intended other than are imposed by the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent of 'theUnited States is as follows:

1. Radio receiving apparatus comprising a radio frequency amplifier, detector and audio frequency amplifier, each of said amplifiers being constituted by a plurality of electron tube stages, a power source of alternating current, a rectification system, a filter circuit connected thereto, and connections from said filter circuit to 'said electron tube stages, the rectified current being supplied first to the last stage of audio frequency amplification and then to the stages of radio frequency amplification and preceding stage of audio frequency amplification in succession. I

2. Radio receiving apparatus comprising a radio frequency amplifier, detector and audio frequency amplifier each of said amplifiers being constituted by a plurality of electron tube stages, a power source of alternating current,a rectification system connected with said source, a filter circuit connected with said rectification system, a resistance in series with one side of said filter circuit and having tapped connections extending to the circuits of said radio frequency amplification stages, detector and the first of the audio frequency amplification stages, and a connection between the opposite side of said filter circuit and the output circuit of the last stage of audio frequency amplification, whereby rectified current is supplied first to the last stage of audio frequency amplification and then to the radio frequency amplification stages, detector and preceding. stage of audio frequency amplification;

3. Radio receiving apparatus comprising a plurality of stages of electron tube amplification including radio frequency amplifier stages, detector and audio frequency amplifier stages, a power source of alternating current, a rectifier system, a filter circuit connected with said rectifier system, a resistance connected in series with one side of said filter circuit, the opposite side of said filter circuit being connected to the output circuit of the last stage of audio frequency amplification,

output circuitsof said radio frequency amplification stages, and the preceding stage of audio frequency amplification, and a separate tapped connection from said resistance intermediate the 1 ends thereof to the output circuit of the detector.

4. Radio receiving apparatus comprising a plurality of electron tube radio and audio frequency amplification stages, a power source of alternating current, a rectification system connected with said source, a filter circuit connected with said rectification system, a resistance connected at one end with one side of said filter circuit and connected at the other end with the output circuits of said radio frequency amplification stages and the first stage of audio frequency amplification, a connection between the opposite side of said filter circuit with the output circuit of a succeeding stage of audio frequency amplification, a common filament circuit-forthe filaments of said radio frequency amplification stages and said first mentioned audio frequency amplification stage, a resistor shunted across said common filament circuit, and a tapped connection extending from said resistor to an intermediate point on said resistance.

5. An amplifier of electrical variations comprising a plurality of electron amplifying stages, a source of anode potential supplied to at least two of said stages having their anode circuits connected in series with respect to said source, and a resistance connected in parallel with one of said anode circuits. another of which is connected to the positive terminal of said source, whereby anode current passing through said another of said anode circuits is at least equal to the sum of the currents passing through the parallel connected resistance and anode circuit.

6. In an amplifier of electrical variations comprising a source'of anode current, a plurality of electron tube amplifying stages, one stage requiring anode current equal to the sum of the anode currents of at least two other stages, an anode current passing through the first mentioned stage and then'through the anode circuit of the other stages. a

'7. An amplifier of electrical variations comprising a source of anode potential, a plurality of electron tube amplifying stages followed by an electron tube power amplifying stage wherein the anode potential is divided between said power amplifying stage and said other amplifying stages, the anode circuits of said plurality of amplifying stages being-in parallel and connected in series with the anode circuit of the power amplifying stage, whereby the current traversing the anode circuit of the power amplifying stage is at least equal to the sum of the currents traversing the other anode circuits.

8. Radio receiving apparatus comprising a plurality of stages of tuned radio frequency amplification, a detector stage, a stage of audio frequency amplification, and an audio frequency power amplifying stage, each of said stages containing an electron tube, means to supply anode current to said tubes comprising a power source of alternating current, a rectifying system and connections from said rectifying system to said stages whereby the rectified current passes through the anode circuit of said power stage and then through the anode circuit of the other stages, the anode circuits of the radio frequency stages being connected in parallel. a tapped connection along said resistance to the GEORGE T. ROYDEN. 

